1. Technical Field
The embodiments herein generally relates to a detection of segment type in a receiver system, and, more particularly, to an early detection of segment type using Binary Phase Shifting Key (BPSK) and Differential Phase Shifting Key (DBPSK) modulated carriers in ISDB-T receivers.
2. Description of the Related Art
Orthogonal Frequency Division Multiplexing (OFDM) is a technique for modulating digital data, which uses a large number of closely-spaced orthogonal sub-carriers. In the OFDM technique, digital data is modulated to the amplitude and the phase of each of the orthogonal sub-carriers within a transmission band. This technique has been widely used in terrestrial digital broadcasting receiver designs such as Integrated Services Digital Broadcasting-Terrestrial (ISDB-T) and Integrated Services Digital Broadcasting-Terrestrial Digital Sound Broadcasting (ISDB-TSB) for OFDM systems, which is assumed as an effective digital modulation scheme for transmitting data at high rate in many wireless applications, where the radio signals are split into multiple smaller sub-signals that are then transmitted simultaneously at different frequencies to the receiver.
A Transport Stream Packet (TSP) in the ISDB-T multiplexing frame is typically a transport stream packet from layers. The order of these TSPs is unique for a given transmission parameter configuration (e.g., transmission mode, guard interval, modulation and coding rate). In an ISDB-T or ISDB-TSB OFDM symbol, there are data carriers, pilot carriers, transmission and multiplexing configuration control (TMCC) carriers, and auxiliary channel (AC) carriers. The ISDB-T standard specifies two kinds of segment types such as Coherent modulated (CM) segments and Differential Modulated (DM) segments. The information about segment type is specified in DBPSK modulated TMCC carrier.
FIG. 1 illustrates a block diagram of a typical ISDB-T receiver 100 that includes (i) a tuner and an Analog to Digital Converter (ADC) block 102, (ii) an Automatic Gain Control (AGC) block 104, (iii) an IF to baseband conversion block 106, (iv) an adjacent channel filter block 108, (v) a sample rate converter block 110, (vi) a Time Domain Synchronisation (TDS) block 112, (vii) a Fast Fourier Transformation (FFT) block 114, (viii) a Frequency Domain Synchronisation (FDS) block 116, (ix) a Transmission and Multiplexing Configuration Control (TMCC) decode block 118, (x) a channel estimation unit 120, (xi) a de-mapper 122, (xii) a frequency deinterleaver 124, and (xiii) a time deinterleaver and Forward Error Correction (FEC) 126. The tuner and ADC block 102 receives an input signal from an antenna. The AGC block 104 controls a gain of the tuner in order to deliver relatively constant amplitude to the ADC block 102. The IF to baseband block 106 converts the input signal (e.g., IF signal) to a baseband signal.
The adjacent channel filter block 108 rejects the adjacent channels from the baseband signal. The sample rate converter block 110 re-samples the baseband signal. The sampling of the baseband signal is different from a baseband symbol rate. The IF to baseband conversion block 106, the adjacent channel filter block 108, and the sample rate converter block 110 constitute to a signal conditioning module. The TDS block 112 detects a mode, and a Guard Interval (GI) of a received signal at the TDS block. The FFT block 114 performs a Fast Fourier transformation of the baseband data and the size of the FFT will be equal to the detected mode. The FDS block 116 locates pilots in the frequency domain, and performs frequency domain synchronization on the pilots. The TMCC decode block 118 performs a TMCC decoding operation to detect a segment type for all the segments. In order to detect Segment type TMCC carrier decoding needs to be done which takes approximately 408 symbols and inherently more channel changeover time when there is a switch across different channels. Accordingly, there remains a need for to reduce the channel changeover time when there is a switch across different channels.